Roka started out as a spider-like Adjuchas Hollow—one of Szayelaporro Granz' artificially created Menos. About 250 years before her transformation into an Arrancar, Szayelaporro sent her and a handful of weaker Hollows to the Rukongai as part of an observation mission to study Shinigami combat tactics.
By the time of the Arrancar arc, Roka was working as a nurse in Las Noches, where she handled medical duties like reattaching Yammy Llargo's severed arm.
It's worth noting that Kubo never actually named this character in the manga, anime, or official databooks. The name "Roka Paramia" comes from the light novel Bleach: Spirits Are Forever With You by Ryougo Narita.
Content compiled by AnimeList.moe from publicly available sources.
